자기지식은 대상화된 자아에 관한 지식이 아니라 자아와 하나인 지식, 즉 그 지식이 곧 자아의 존재이기도 한 그런 경지를 가리킨다. 맹자가 보기에, 인의를 본성 그대로 구현한 요순의 상태는 자기지식을 완전하게 구현하는 성인의 경지를 대표한다. 소크라테스에게 있어서 자기지식은 미지의 성역에 속하면서 아이로니로 표현되며 아이로니에 의하여 일깨워진다. 자기지식은 직접 겨냥할 수 있는 목적이 아니라 그것의 결여에 대한 자각에 의하여 확립되는 부정적 기준이라는 특징을 가진다. 칸트의 아프리오리와 이념은 자기지식의 성역적 의미를 훼손하지 않고 이론적 논의에 의하여 그것을 규정할 가능성을 열어 준다. 키에르케고르가 그의 저작술로 구현한 간접전달의 아이디어는 독자들로 하여금 그들의 내면에서 자기지식의 결여를 자각으로써 그들의 자아가 이념에 합치되는 방향으로 형성되도록 이끌려는 발상을 나타낸다. 이념으로서의 자기지식은 ‘신 앞에서의 자기멸각’을 의미 요소로 포함한다.
Mencius suggested what may be called ‘stages of self-cultivation’ by saying “Benevolence and righteousness were natural to Yao and Shun. Tang and Wu made them their own. The five chiefs of the princes feigned them.” It means that Yao and Shun embodied benevolence and righteousness as perfect self-knowledge by nature, and Tang and Wu made them their self-knowledge by their willful efforts, while the five chiefs of the princes did not get out of the self-deception. But the self-knowledge of Yao and Shun are to be seen as the negative standard which can be confirmed only by recognizing its inaccessibility. It was his ignorance expressed by irony that made Socrates the most prominent teacher who inspired his pupils to self-knowledge in the history of western education. For Socrates, the pursuit of self-knowledge is the necessary condition of worthwhile life, in spite of its inaccessibility. The kind of self-knowledge attainable to the existing person is the knowledge of its absence and incessant striving for it. Kant s transcendental philosophy sheds light on understanding the unknown dimension of self-knowledge. He opened the possibility that self-knowledge may be construed as the a priori idea which constitutes the limit of reason and being. Kierkegaard inherited the sense of self-knowledge that Kant illuminated. For Kierkegaard, the self-knowledge amounts to faith which can be defined as “the state of self when [it] rests transparently in the power that established it.” ‘Despair’ as the opposite of faith is nothing but the absence of self-knowledge. His idea of ‘indirect communication’, proposed for overcoming the despair and awakening the faith, can serve as a mirror to reflect what self-knowledge is. Focused on the negativity of self-knowledge in regard to its inaccessibility, we have inevitably need of the divine intervention or revelation of the transcendent being. We may be expected to relate our selves to the divine selves only if we realize thoroughly our ignorance and sinful being. It is not quite wrong to think of ‘self-annihilation before God as part of self-knowledge.